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VAT Fundamentals

A timeless guide to adding and removing VAT with editable rates, written to stay useful as a formula reference rather than a fixed legal statement about any one tax regime.

Key formulas

Add VAT
gross = net x (1 + rate)
Remove VAT
net = gross / (1 + rate)
VAT amount
VAT = gross - net

How to think about VAT maths

VAT questions are often simpler than they look once you separate the net amount, the VAT amount, and the gross total. The rate itself should stay editable because the maths is timeless even when the tax setting changes.

This site treats any default rate as a convenience only, not as a permanent rule.

Worked example

If a net amount is 100 and the VAT rate is 20%, the gross amount is 120. Going the other way, a gross amount of 120 divided by 1.20 returns a net amount of 100.

That reverse step matters because simply subtracting 20% from the gross amount is not the same calculation.

Assumptions and limits

VAT treatment can vary in real life. Use these pages as formula tools, then confirm any policy, invoicing, or compliance details separately.
  • The calculators only use the rate you enter.
  • They do not decide which goods or services should carry a particular rate.
  • Mixed-rate, exempt, or jurisdiction-specific treatment should be handled outside the basic formula.
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